Device for grinding work surfaces curved in the longitudinal direction



y 1962 o. BRETSCHER 3,046,702

DEVICE FOR GRINDING WORK SURFACES CURVED IN THE LONGITUDINAL DIRECTION 3 Sheets-Sheet 1 Filed Dec. 17, 1958 Fig. 2

I N VENTOR. 0 T70 6 PFCHR BY 2 July 31, 1962 Filed Dec.

0. BRETSCHER 3,046,702 DEVICE FOR GRINDING WORK SURFACES CURVED IN THE LONGITUDINAL DIRECTION 3 Sheets-Sheet 2 INVENTOR. 07-7-0 zwszrr/me 0. BRETSCHER DEVICE FOR GRINDING WORK SURFACES CURVED IN THE LONGITUDINAL DIRECTION July 31, 1962 3 Sheets-Sheet 3 Filed Dec. 17, 1958 INVENTOR 0 T'Ta 56573'0/5? BY 2 ites? tates Claims priority,'application Switzerland Dec. 17, 1957 I 3 Claims. (Cl. 51-92) The present invention relates to a device for grinding work surfaces curved in the longitudinal direction in which the grinding wheel is moved during operation.

The invention is characterized by the fact that a cam is provided to effect adjustment of the grinding wheel relative' to the work table, the cam being moved in dependence on the'reciprocating movement of the work table, mechanical follower members being associated therewith of which the control deflections are transmitted to the grinding wheel via intermediate links.

' A number of embodiments of the invention are represented in the drawing in which:

FIG. 1 is a diagrammatic side view of a device for curved work surfaces in which a. grinding wheel holder is suspended from an eccentric shaft;

FIG. 2 is a side view of the control members for the adjustment of the grinding wheel;

FIG. 3 is an elevation, partly in section, of a device according to FIG. 2; I

FIG. 4 is a variant of the control members, and

FIG. 5 is a variant of the height adjustment of the grinding wheel holder.

FIG. 1 shows a device in which a cross slide 27 is displaceably arranged in guideways in an upright 26. A bracket 16 carries a grinding wheel spindle holder 17 on an eccentric shaft 15 arranged in the bracket 16 (FIG. 3). Attached to one end of the eccentric shaft 15 is alever 14 equipped with a roller or cam follower 23 (FIG. 2). A hand operated spindle 28 cooperable with the bracket 16 to permit manual adjustment of the position of the grinding wheel 18 relative to the work piece 2.

The work 2 is placed on a work table 1 (FIG. 2). An

. electric motor 6 drives the work table 1 via a rack 3, a

gear 4 and a worm gear 5 so that the table 1 performs a reciprocating movement. A transmitter, as for example shown in my United States Patent 2,312,620, granted November 12, 1957, i.e. a conventional servo-motor or synchro-generator 7, is directly connected with and driven by the motor 6 as by means of a gear or the like.

This electrical connection for the purpose of transmitting rotation between the motor 6 and the motor 8 replaces a mechanical drive and is termed electrical shaft.

The motor 8 drives a cam 13 via a worm gear 9, 10 and gears 11, 12, the cam 13 being fixed or interchangeable. roller 23 arranged on the =lever14.

The cam 13 is symmetrical so that it causes the same displacement of the cam follower or roller 23 and the lever 14, respectively, when moved to the left or the right from a particular central position.

A tension spring 20 holds the lever 14 and the cam follower or roller 23 respectively in operative connection with the cam 13. Swivelling of the lever 14 rotates the eccentric shaft 15 and displaces the grinding wheel spindle holder 17 relative to the stationary bearing bracket 16 and the work table 1 respectively.

In order to employ the device for grinding flat, straight work surfaces, means are provided to eliminate the raising and lowering mot-ion of the grinding wheel 18. Pro- The cam 13 is followed by the cam follower or ten vided for this purpose is an eccentric lever 19 which actuates a pin 24 capable of lifting the lever-14 from the cam 13 and thereby holding the cam follower or roller 23 outside the operative range of the cam 13. The eccentric lever 19 is connected to an electric switch Patented July 31, 1962 r 21 which is in connected with an auxiliary circuit the right.

rection of feed of the table 1 and, respectively, of the motor 6, the direction of rotation of the generator 7 is reversed. This change is transmitted to the motor 8 and the gear members connected therewith, and to the cam 13. The gear members 9 through 12 limit the angle of rotation of the-cam 13 in such a manner that it perform only a fraction of a revolution during one stroke of the table 1.

The angle of rotation of the cam 131's preferably larger than The device is then set so that the cam- 13 is in its central position when the centre of the work table 1 and the work 2 respectively is beneath the grinding wheel 18'. Displacement of the table 1 to the left or to the right thereby causes the cam 13 to be rotated to the left or to Since the work 2 is to be thinned towards its ends, the cam 13 is designed so that, on being rotated, it will actuate the lever 14 in such a manner that the grinding wheel will perform a downward movement from the centre towards the ends of the work 2 and the table 1 respectively.

Instead of performing the raising and lowering movement of the grinding wheel 18 by means of the eccentric shaft 15, it may be performed by equipping the lever 14 v with a threaded nut 29 ('FIG. 5) fixed relative to the axis of rotation of the lever but rotatable therewith, in which a spindle 30 is raised and lowered by the swivelling cam 32 is a reproduction of the curved surface of the work 2 to be obtained, the elevation of the cam 32 being preferably greater than the convexity of the work 2.

The length of the cam 32 is advantageously shorter. than A a the length of the stroke of the work table 1 and therwork I 2 respectively.

The displacement of the straight cam 32 is effected by means of'a spindle 33 driven by the motor 8 direct or via a gear 34. Rotation of the spindle 33 displaces a threaded nut 35 connected with the cam 32.

The control cams (13 and 32) are interchangeable in the present device so that various cam designs will enable various curvatures to be obtained on the work. The maximum deflection of the lever 14 determines the maximum stroke of the grinding wheel 18.

The control cams 13 and 32 respectively could also be replaced by a slotted cam which is engaged by a control finger arranged on the lever 14.

The present device may, by way of example, be em- 3 ployed for grinding guideways on machine beds, a particular advantage residing in the fact that very small height adjustments, i.e. very flat curves can be produced with a high degree of precision. In particular, it is possible to grind guideways in machine tools arcuately, the arc height being in the magnitude of some hundredths to some thousandths of a millimetre. In operation, this superelevation will be equalized under operating pressure.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A device for grinding substantially flat work pieces so as to arch said work piece in one direction, comprising a rectilinearly reciprocal work table for supporting a work piece, a grinding wheel, a support'located above said table and rotatably carrying said grinding wheel, said support being mounted for raising and lowering movements, an electrical generator operatively connected to said work table, an electric motor in circuit with said electrical generator, said electric motor being energized by said electrical generator in timed relation with the movement of said work table, an interchangeable cam operatively connected with said electric motor, cam follower means co operating with said cam and with said grinding wheel so that the deflections generated from the cam are transmitted to the grinding wheel for regulating the elevationadjusting operation in dependence on the motion of said work table, whereby the work piece may be ground with a high degree of precision, said cam follower means including a swivelling lever having a roller engaging said cam so as to follow its movements, said lever being in operative connection with said support, said support being eccentrically mounted so that rotation of said lever will adjust the grinding wheel.

2. A device for grinding substantially flat work pieces so as to arch said work piece in one direction, comprising a rectilinearly reciprocal work table for supporting a work piece, a grinding wheel, a support located above said table and rotatably carrying said grinding wheel, said support being mounted for raising and lowering movements, an electrical generator operatively connected to said work table, an electric motor in circuit with said electrical generator, said electrical motor being energized by said electrical generator in timed relation with the movement of said work table, an interchangeable cam 4 operatively connected with said electric motor, cam follower means cooperating with said cam and with said grinding wheel so that the deflections generated from the cam are transmitted to the'grinding wheel for regulating the elevation-adjusting operation in dependence on the motion or said work table, whereby the work piece may be ground with a high degree of precision, said cam follower means including a swivelling lever having a roller engaging said cam so as to follow its movements, said lever being in operative connection with said support, said support being eccentrically mounted so that rotation of said lever will adjust the grinding wheel, and means provided to remove said roller from engagement with said cam, said last recited means being connected to the electrical supply to said motor. a

3. A device for grinding substantially flat work pieces so as to arch said work piece in at least one direction, comprising a rectilinearly reciprocal work table for supporting a work piece, a grinding'wheel, a support located above said table and rotatably carrying said grinding wheel, said support being mounted for raising and lowering movements, an electric generator operatively connected to said work table, an electric motor in circuit with said electric generator, said electric motor being energized by said electric generator in timed relation with the movement of said Work table, an interchangeable cam operatively connected with said electric motor, a pivot support to which said cam is swivelably and removably connected, cam follower means cooperating with said cam and with said grinding wheel, said cam having a cam surface designed to impart pivotable movement to said cam follower means, and reduction gear means operatively connected between said electric motor and said cam so that the deflections generated from the cam are transmitted to the grinding wheel for regulating the elevadon-adjusting operation in dependence on the motion of said Work table, whereby the work piece may be ground with a high degree of precision.

References Cited in the file of this patent UNITED STATES PATENTS 376,814 Coleman Jan. 24, 1888 1,831,412 Ellenbecker Nov. 10, 1931 2,767,520 Rudnicki Oct. 23, 1956 2,812,620 Bretscher Nov. 12, 1957 

